Surface-enhanced Raman spectroscopy (SERS) has been employed for label-free analysis of microorganisms and biomolecules to exploit its 106˜1010 times enhancement in the Raman signal.
A variety of SERS substrates have been prepared by, e.g., disposing colloidal metal nanoparticles on a surface, roughening a metal surfaces to possess nanometer-scale features, or creating nanostructures on a surface by lithography. See, e.g., Demirel, M. C. et al., Biointerphases 4, 35-41 (2009); Stern, E. et al., Nature Nanotech., 5, 138-142 (2010); Nie, S. et al., Science, 275, 1102-1106 (1997); Fang, Y. et al., Science, 321, 388-392 (2008); Li, J. F. et al., Nature, 464, 392-395 (2010); Tripp, R. A. et al., Nanotoday, 3, 31-37 (2008); Kao, P. et al., Adv. Mater., 20, 3562-3565 (2008); Shachaf, C. M., et al., PLoS ONE, 4, e5206-e5217 (2009); and Qian, X. et al., Nature Biotechnol., 26, 83-90 (2008).
Yet, there is still great need to develop new SERS substrates suitable for detecting biomolecules or microorganisms in a rapid, reliable, and uniform manner.